The present invention relates to an absorption cooling apparatus that is used as an outdoor machine for an absorption air conditioning system and which cools the heat transfer medium used to activate the cooling operation of an indoor air conditioner. The invention particularly relates to an improvement of the mechanism for cooling the heat transfer medium.
Among the known absorption cooling apparatuses is the one shown in FIG. 3 that has an evaporating/absorbing section of dual pipe type in which a cylindrical outer pipe 1 and a coaxial evaporating pipe 2 that penetrates both the top and bottom of the outer pipe 1, with an evaporating/absorbing compartment 3 being formed between the inner peripheral surface of the outer pipe 1 and the outer peripheral surface of the evaporating pipe 2. This evaporating/absorbing section has refrigerant dispense pipes 4 that penetrate the top plate of the outer pipe 1 to project into the evaporating/absorbing compartment 3. A liquid refrigerant is dispensed through the pipes 4 onto the outer peripheral surface of the evaporating pipe 2 so that the heat of vaporization resulting from the evaporation of the liquid refrigerant cools a heat transfer medium (which is usually cold water and hereunder referred to as "cold water") that passes through the evaporating pipe 2 from top to bottom or vice versa. The evaporating/absorbing section also has absorbing liquid dispense pipes 5 that penetrate the top plate of the outer pipe 1 to project into the evaporating/absorbing compartment 3. The refrigerant vapor formed in the compartment 3 is absorbed by an absorbing liquid that is dispensed through those pipes 5 onto the inner peripheral surface of the outer pipe 1. The absorbing liquid L that has been diluted upon absorbing the refrigerant vapor collects in the bottom of the outer pipe 1, from which it is discharged to the outside.
In order to enhance the efficiency with which cold water is cooled in the evaporating/absorbing section, the velocity of the cold water flowing through the evaporating pipe 2 must be increased. The cold water flowing through the evaporating pipe 2 is cooled more efficiently in portions close to the wall surface than in the portion close to the center of the pipe. At low velocity, the cold water forms laminar flows and the stream flowing through the center of the evaporating pipe 2 does not easily mix with the stream flowing along the wall surface, thus contributing to a lowered cooling efficiency. In addition, the evaporating pipe 2 itself is cooled and the refrigerant water dispensed onto the outer peripheral surface of the evaporating pipe 2 does not easily evaporate. Hence, the cold water flowing through the evaporating pipe 2 desirably forms turbulent flows. In order to create turbulent flows, the velocity of the cold water must be increased by inserting a turbulence promoter such as a coil or reducing the diameter of the evaporating pipe 2. However, the insertion of a turbulence promoter can increase the cost and weight of the equipment. If the diameter of the evaporating pipe is reduced, a great number of such evaporating pipes must be used or their height (length) has to be increased in order to secure the necessary surface area for the evaporation of the refrigerant and this again increases the cost of the equipment.
In the conventional evaporating/absorbing section, the evaporating pipe 2 penetrates both the top and bottom of the outer pipe 1 and cold water flows either from top to bottom or vice versa. The cold water always passes through the bottom of the outer pipe 1, so without some special structural design, it may be subject to the heat of the hot absorbing liquid L collecting in the bottom of the outer pipe 1 and this will result in an even lower cooling efficiency.